A poison ivy rash is an allergic reaction to the oils on the plant’s leaves. Poison ivy can spread if a pet carries the oil on its fur, but a poison ivy rash isn’t contagious.

Published: May 16, 2019 | Updated: October 12, 2022

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Poison ivy isn’t contagious and the oil that causes the rash and blisters can be washed off the skin quickly while the reaction lasts for a few weeks. Pets can carry the oil from the plant’s sap in on their fur, but the oil typically doesn’t transfer from person to person.

It’s important to know that the oil doesn’t rely on the living plant to cause a reaction. The irritating oil can persist on surfaces like gardening tools, gloves and other items until it’s washed off.

When the oil contacts skin, the allergic reaction begins. First, it’s an itch that starts a few hours to several days later.

“A poison ivy reaction can range from a mild itch to large blisters on the skin,” said Gregory E. Shaw, M.D., pediatrician with Norton Children’s Medical Group – Lakeview in St. Matthews. “It’s difficult, but you really need to avoid scratching. Scratching exposes the rash and blisters to bacteria, which can cause an infection.”

It may seem like the rash is spreading because your body’s allergic reaction can occur in stages where the oil made contact.

How to treat poison ivy

• Soaking in cool water or applying wet compresses like a washcloth to the rash can give relief from the itching.
• Over-the-counter topical preparations with hydrocortisone can relieve the itch.
• Over-the-counter skin protectants like calamine can dry weeping rashes.
• Baking soda or colloidal oatmeal relieve itching.
• Antihistamines like Benadryl are not typically recommended because the allergic reaction is not related to histamine.

If you have any of the following severe poison ivy symptoms, contact a health care provider

• Temperature of more than 100 degrees
• Pus or soft yellow scabs on the rash
• The itching interferes with your sleep
• The rash includes your eyes, mouth or genital area
• The rash is widespread — covering more than a quarter of your body
• Difficulty breathing

Poison ivy prevention

The U.S. Food and Drug Administration offers these tips for preventing a poison ivy rash:

• Learn what poison ivy looks like. Poison oak is not common in Kentucky or Indiana, but poison sumac is found in our area.
• Wash garden tools and gloves regularly. If you think you may be working around poison ivy, wear long sleeves, long pants tucked into boots, and impermeable gloves.
• Wash your pet if it may have brushed up against poison ivy or sumac. Use pet shampoo and water while wearing rubber gloves, such as dishwashing gloves. Most pets are not sensitive to poison ivy, but the oil can stick to their fur and cause a reaction in someone who pets them.
• Wash your skin in soap and cool water as soon as possible if you come in contact with a poisonous plant. The sooner you cleanse the skin, the greater the chance that you can remove the plant oil or help prevent further spread. A dish soap like Dawn helps remove the poison ivy sap from the skin.